Stars: Miracle in the sky
When I was young, I used to think stars were heavenly and they just appear in the sky from nowhere. Infact, I used to think they are small the way they appear from a distance yet dazzling.
That nursery rhyme twinkle twinkle little star... didn't help me realise I was wrong either.
I eventually learnt that stars are big, a medium sized star has a diameter of 1.4 million km. I also learnt that stars live and die just like we do as humans but they have longer lifespan. Lest I forget , I found out that they come in different colours too, not just white.
How stars are born and how they die
Stars are born deep inside gas clouds called nebulae, planetary nebulae is found in space. Gravity pulls the nebulae to form protostars, protostars undergo increased temperature and pressure due to their own internal gravity thereby causing the hydrogen present in them to form helium. During this process, heat and energy is released and stars begin to shine.
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This process where hydrogen changes to helium is a nuclear reaction. It is regarded as nuclear fusion because the Nuclei of four hydrogen atoms joins together to form helium. It is this process that brings about heat and light which keeps the star shining.
The star will continue to shine (remain alive) as long as there is hydrogen to undergo nuclear fusion.
The lifespan of a star depends on its mass. The bigger a star is, the faster it burns out. Small stars live for about trillion years, a medium star like the size of the sun lives for about ten billion years while large stars live for millions of years. (yes stars can live longer than humans and the universe).
These stars explode in core-collapse supernovae, some of the most energetic explosions in the universe.
As they run out of hydrogen to fuse in their cores, they swell into red giant stars before shedding their outer layers. The remnant left behind in these planetary nebulae is a white dwarf star. White dwarfs eventually fade into black dwarfs.
A black dwarf is what remains after a star dies. Specifically it is a white dwarf that has cooled sufficiently that no longer emits significant heat or light. A black dwarf is usually confused with black holes, black stars and neutron stars but they are different.
A black star has so much gravity, it is gravitational and it pulls other objects and stars. A blackhole is an area in space having strong gravity effects such that nothing cab escape from it and neutron stars are regarded as the smallest stars yet they are 1.4 times as big as the sun.
However because the time required for a white dwarf to reach this state is calculated to be longer than the current age of the universe which is 13.8 billion years no black dwarfs exist in the world yet. The world is too young to create a black dwarf yet.
It will take billions of years for a white dwarf to cool completely as the temperature of a white dwarf is said to be up to 100million degrees. So basically we can say that in the world today, stars that have stopped giving out heat finish up as white dwarfs waiting to become black dwarfs.
Do you know that the sun is regarded as a star?
The sun is regarded as our closest, most familiar. This is because the sun contains hydrogen and helium as well and it is produced as a result of nuclear fusion. The sun shines and emits heats too just like the star. It is only closer to us and not as distant as the stars.
According to their system of classification, the Sun is known as a yellow dwarf star. This group of stars are relatively small, containing between 80% and 100% the mass of the Sun. So the Sun is at the higher end of this group, stars in this classification last for about 10 billion years.
If you are still wondering what the fuss is about stars like I wondered, read on
Why are stars important to us?
Have you ever heard of the saying that we are all made of stardust? yes, it sounds awkward but stars are like the basis of our existence, every molecule in our body is related to the core of a star.
Stars are said to aid agriculture as well and also they are the reason all other heavier elements like Iron and calcium exists. Also without the star, the sun or any life on earth can't thrive. So next time you sight a star in the sky, remember how special it is.
Growing up, we did hear fabrications about starts, like some did say a star falls at every person’s passing/demise; I wonder how many stars would be left in the big sky now if that was the case. Lol. I love this write up.
I'm fascinated with stars and things right up in the sky.
Me too....
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